Magnesium, the lightest structural metal with a density of about two-thirds of aluminum, is abundant on Earth and biocompatible, and thus widely considered as an emerging “green” metal with tremendous potential to improve energy efficiency and system performance from aerospace, defense, automobile, mobile electronics to biomedical applications. However, typical synthesis and processing methods (alloying, even with rare earth elements, and thermomechanical processing) have reached certain constraints in further improving the properties of magnesium, such as strength, low-temperature ductility and thermal stability, for widespread applications.
Properties of metals are typically controlled by alloying and thermomechanical processing. However, atomic vacancies and interstitials, dislocations, internal boundaries, and precipitates achievable for property tuning are constrained by phase diagrams and the intrinsic properties of a system. An example is the lightest structural metal, magnesium, which has great potential to improve fuel-efficiency and system performance due to its light weight properties. However, typical methods used to enhance properties are still generally not able to provide satisfactory property enhancement due to the difficulty in obtaining fine, strong and high temperature stable precipitates and high density internal boundaries (e.g., grain boundaries or twin boundaries). The low strength, low stiffness, and poor high temperature stability severely restrict the widespread applications of magnesium. To break the apparent property ceilings of magnesium, as well as other metals, much stronger ceramic particles can be introduced into metal matrices. Unfortunately, micrometer-sized ceramic particles severely deteriorate the plasticity and machinability of metals, and also fail to provide effective Orowan strengthening due to the large size and spacing between particles. One might expect that nanometer-sized ceramic particles have the potential to significantly improve strength while maintaining or even improving plasticity of metals by interacting with dislocations (Orowan strengthening) and grain/phase boundaries (Zener pinning). It has, however, been observed that dispersing nanoparticles uniformly in metal matrices, especially in magnesium, a prerequisite for significant property enhancement, is extremely difficult due to the lack of an engineered repulsive force between nanoparticles. High energy ball milling, the most effective technique for powder mixing, can disperse a low volume fraction (less than 3 vol. %) of nanoparticles in a metal matrix with optimized parameters, but micro-clustering is still a serious issue when the volume fraction of nanoparticles is high. High energy ball milling also suffers from contamination, demanding processing conditions to avoid explosion, and involving high cost and low production volume.
It is against this background that a need arose to develop the embodiments described herein.